Method for conditioning artificial thread



Jan. 14-, 1936. HQFMANN zfizxfiml METHOD FOR CONDITIONING ARTIFICIAL THREAD Filed April 2, 1950 INVENTOR He /yo 17.5fm 722a ATTORNEY Patented Jan. 14, 1936 PATENT OFFIQE METHOD FOR CONDKTEONING ARTIFICIAL THREAD Hugo Hofmann, Johnson City, Tenn, assignor to American Bemberg Corporation, New York, N. Y., a corporation of Delaware Application April 2, 1930, Serial No. 440,938

6 Claims.

In the production ofartificial threads by the cuprammonium stretch-spinning process, a num ber of filaments are formed by forcing the cellulosic material through a nozzle having a corresponding number of small holes. These filaments are initially stretched to some extent by the force of the liquid carrying them, in a plastic state, through the spinning nozzle. The filaments, grouped together as a thread, are thereafter fixed or hardened by passing them through an acid or a salt solution, and are then assembled upon a reel or in a spinning pot.

It has recently been found that by performing most of the stretching outside of the spinning funnel, a thread of greatly increased tear-resistance or breaking strength may be produced. This stretching is accomplished by maintaining the speed of the thread constant as it leaves the spinning nozzle and increasing its relative speed as it passes over a later portion of its path of travel, for instance, by passing it over two drawing rolls, the last of which is operated at a greater circumferential speed than the first.

The threads produced by this procedure are of increased breaking strength, but this increase in breaking strength is accompanied by a decrease in elasticity.

It is an object of this invention to provide a method and means for producing artificial threads of increased breaking strength and increased elasticity. It is a further object of the invention to produce an artificial thread of improved characteristics. Further objects will become apparent.

I have found that by stretching the thread after it leaves the spinning funnel and shrinking it before the fixing solution is applied, a thread of increased tear-resisting or breaking strength may be produced without an attendant loss in elasticity.

In describing an embodiment of my invention, reference will be made to the drawing in which is shown a perspective view of a series of units adapted to accomplish my improved results.

In the drawing, the numeral l denotes a stretch spinning funnel of standard construction. The thread 2 from the funnel I passes over the rods 3 and 4. These rods serve to change the direction of the thread and are preferably of small diameter and of some material, such as nickel or Monel metal, which will cause as little friction as possible between the thread and the rod.

The thread 2 then passes over a stationary rod 5 of increased diameter, to give greater length of contact, and of some material, such as porcelain or glass, which results in higher friction between the thread and the rod. From the rod 5 the thread passes around the reel 6 which is made up of a series of spaced glass, or porcelain, rods I supported upon a frame fixed to a shaft 8.

The thread 2 leaving the reel 6 passes over a rod e which assists in removing it from the rods l. The thread then passes through a porcelain guide Hi where an acid, or salt, fixing solution is applied and from this bath it passes to one of a row of winding reels l2 which are fixed to and rotated by the shaft l3. The acid guides It are supported upon a rod H which may be reciprocated to give a proper windingaction.

The thread leaving the funnel is partly coagulated but still has a high plasticity. The friction between the rods 1 and the thread 2 should be such that the thread will be drawn along at the circumferential speed of the reel. The friction between the stationary rod 5 and the thread may be regulated, by adjusting the rod 5, so that the desired tension will be put upon the thread between this rod and the reel 6 and so that only a slight amount of this tension will be transmitted to the thread between the funnel I and the rod 5. With this arrangement the speed of the reel 6 may be regulated to produce the desired amount of stretching in the still plastic thread between the rod 5 and the reel 5, up to the limit of elasticity of the thread, and this may be accomplished without substantially increasing the tension upon the filaments within the nozzle.

In order to obtain the desired slackening or shrinking of the thread between the reel 6 and the winding reel [2, the latter is rotated at such a speed that the lineal speed of the thread at the circumference of the reel l2 will be less than the lineal speed of the thread leaving the reel 8. The application of the fixing solution in the guide l0 results in the fixing or setting of the slackening thread. Since the elasticity of the thread is almost proportional to the shrinking of the elongated thread, the desired elasticity may be obtained by regulating the degree of reduction in the tension upon the thread passing through the guide in which the fixing bath is applied.

The reel 6 made up of a series of glass or porcelain rods spaced around the circumference of the reel provides a device from which the thread may be removed more easily than from the roll or rod customarily used in this type of work. The discontinuous surface resulting from this arrangement avoids the sticking which attends the use of a roll. The rod 9 is positioned to assist in this removal.

By following my procedure a thread may be produced which has a tear-resistance of over 2.3 grams per denier and an elasticity of over 10% in a dry state, and over 25% in a wet state, the term elasticity being used to express the percentage elongation of the thread, over its original length, as it is stretched until it breaks.

Instead of using the winding reel l2 for assembling the thread, a feed roll, positioned above a spinning pot of standard construction, may be used and the thread from the feed roll may be assembled in the usual manner in the spinning pot.

Although I have described in detail a single embodiment of my invention, it is not intended to thereby limit it to the particulars described, it being apparent that many modifications and applications of it may be made by one skilled in the art.

What I claim is:

1. In the production of threads of the class described, the steps comprising precipitating the threads, stretching and shrinking the thread, then subjecting it to a fixing solution.

2. In the production of artificial thread by the cuprammonium stretching spinning method, the steps comprising stretching the thread after it leaves the spinning funnel and slackening it before it is subjected to a fixing solution and then subjecting the thread to the fixing solution.

3. In the production of artificial thread, the steps comprising spinning the thread, precipitating it, applying a tension to the thread to elongate it after it has been precipitated, and decreasing the tension before applying a fixing solution in order to obtain the desired degree of elasticity.

4. In the production of artificial thread by the 10 cuprammonium stretch spinning method, the steps comprising applying a tension to elongate the filament and decreasing the tension before applying an acid fixing solution and then ap-- plying the fixing acid to the thread. 15

5. In the production of artificial filaments, the steps of extruding the filaments, precipitating them, stretching them, allowing them to relax, treating them with a setting solution while they are relaxed, and winding or reeling them with- 20 out applying further tension.

6. An artificial silk thread from the cupram monium process produced by stretching and shrinking the thread before subjecting it to the fixing solution and having a tear-resistance of 25 over 2.3 grams per denier and an elasticity of over 10% in the dry state.

' HUGO HOFMANN. 

